White blood cells in urine, medically known as pyuria or leukocyturia, indicate an underlying issue within the urinary system. While urine is typically a sterile fluid, their presence suggests the body is responding to an irritant or invader, signaling a medical condition requiring attention.
What White Blood Cells in Urine Signify
White blood cells (WBCs), also called leukocytes, are a fundamental part of the body’s immune system, defending against infection and foreign substances. Produced in the bone marrow, they are found throughout the body, constantly working to protect it. Their appearance in urine signifies an immune response within the urinary tract, which includes the kidneys, ureters, bladder, and urethra.
Their presence means the immune system has been activated to address a problem within this system. This response could be due to inflammation, irritation, or an infection. White blood cells in urine act as a signal that the body is actively trying to fight off something it perceives as harmful.
Primary Causes of White Blood Cells in Urine
The most frequent reason for white blood cells in urine is a urinary tract infection (UTI). When bacteria enter the urinary tract, they multiply, triggering an immune response where the body sends white blood cells to combat the invading microorganisms.
Untreated UTIs can lead to kidney infections (pyelonephritis), causing a significant increase in white blood cells as the immune system works to clear the infection within these vital organs. Kidney stones can also lead to white blood cells in urine by causing irritation and inflammation within the urinary tract. These hard deposits can obstruct urine flow or cause physical damage.
Sexually transmitted infections (STIs) can also cause urinary tract inflammation, leading to white blood cells in urine. Conditions like chlamydia and gonorrhea can affect the urethra and surrounding areas. Beyond infections, non-infectious inflammation from conditions such as interstitial cystitis, a chronic bladder condition, can cause white blood cells to appear in urine. Some medications can also contribute by causing urinary tract irritation. In rarer instances, conditions like appendicitis, pelvic tumors, or certain systemic diseases can lead to an elevated white blood cell count in urine.
How White Blood Cells in Urine Are Detected
White blood cells in urine are primarily detected through a urinalysis, a common laboratory test. This process often begins with a dipstick test, where a chemically treated strip dipped into a urine sample indicates the presence of leukocyte esterase, an enzyme found in certain white blood cells.
For a more precise assessment, a microscopic examination of the urine sediment is performed. After centrifuging the sample to concentrate cells, a lab technician views the sediment under a microscope to count white blood cells. Results are typically reported as the number of white blood cells per high-power field (HPF), with 0-5 HPF generally considered normal. A “clean catch” urine sample is important to ensure accurate results and prevent contamination.
Next Steps and Treatment
If white blood cells are found in your urine, consulting a healthcare professional is an important next step. Their presence signals an underlying issue, not a diagnosis itself, and the specific cause needs to be identified.
A doctor may order further diagnostic tests to pinpoint the origin. These can include a urine culture to identify specific bacteria if an infection is suspected. Blood tests or imaging studies, such as an ultrasound or CT scan, may also investigate the kidneys or other urinary system parts, especially if kidney stones or obstructions are suspected.
Treatment for white blood cells in urine depends entirely on the identified underlying cause. For bacterial infections, antibiotics are typically prescribed. Kidney stones might require pain management or procedures like lithotripsy. For inflammatory conditions, specific medications may reduce inflammation. Self-treatment is not advised, as proper diagnosis and targeted therapy are essential for resolution.